Brain injuries can lead to widespread deficits in a range of functions — from language to motor skills and cognition — and the effects may be longer-lasting than researchers thought, especially in young children who suffer traumatic blows to the head.

In research published in the journal Pediatrics, Vicki Anderson, director of critical care and neuroscience research at the Murdoch Children’s Research Institute in Melbourne, Australia, and her colleagues found that children with brain injuries continue to have problems with cognition for a decade after their trauma. In previous studies, Anderson showed that these effects can last for as long as five years.

The new study followed a group of 40 children aged 2 to 7 with traumatic brain injuries, generally caused by car accidents or a bad fall. They were given a battery of cognitive, social and behavioral skills tests at the time of their injury, and then tested again at three months, six months, 18 months, five years and 10 years after the injury.

Overall, the children with the most severe brain injuries showed the most deficits over the course of study, while those with milder injuries showed the least problems, compared with a group of 16 control participants who did not have brain injuries.

Most of the deficits occurred in higher learning skills such as organization, planning and reasoning, because these are centered in the frontal regions of the brain, which are most often affected in head injuries. These regions are also the ones that develop fastest early in life, so any injury that disrupts the normal trajectory of nerve growth can have long-lasting effects, says Anderson.

Despite the fact that the brain is plastic, meaning that it has redundancies and possesses a remarkable ability to compensate for deficits, when young children injure their brains, they suffer from a double whammy. First, because their brains are still developing, they don’t have the advantage of falling back on a fertile, fully developed brain. Second, their brain development after the injury continues to lag behind, appearing not to catch up to normal. “If you look at the trajectory of improvement over time, normal kids have one trajectory, while those with brain injuries have the same trajectory but start out at a much lower point,” says Anderson.

But there are reasons to hope as well. Some experts believed that brain injuries at a young age were so disruptive that the brain could not continue developing at all, arresting at whatever stage it was injured. But Anderson’s group found evidence that after blows to the head, children’s brains could start developing again — it’s just that they can’t recover completely to compensate for the effect of the trauma.

They also found that families and physicians can help children improve by providing rehabilitation and a supportive environment. Those who had robust support networks showed greater gains in cognitive function 10 years later than those who didn’t. Intervening early with these strategies, soon after the injury, also helps. “Early intervention sets the child up for optimal recovery,” says Anderson, “and helps the parents to cope better as well.”

She stresses that these results apply to children with major traumatic brain injuries, and not to those who suffer milder concussions or bumps on the head. And while the blows appear to have lasting effects, at least some of them can be lessened with prompt and supportive care.

Alice Park is a writer at TIME. Find her on Twitter at @aliceparkny. You can also continue the discussion on TIME’s Facebook page and on Twitter at @TIME.